Process for adipic acid manufacture

ABSTRACT

DISCLOSED HEREIN IS A PROCESS FOR THE MANUFACTURE OF ADIPIC ACID, A REACTANT IN THE PREPARATION OF 6,6 NYLON, COMPRISING REACTING CYCLOHEXENE AND ACETALDEHYDE IN THE PRESENCE OF OXYGEN AND A CATALYST CONSISTING OF A SALT OF ONE OF THE METALS VANADIUM, TUNGSTEN, MOLYBDENUM, OSMIUM OR RUTHENIUM, SAID PROCESS OPTIONALLY EMPLOYING A COCATALYST CONSISTING OF AN INORGANIC NITROGEN-CONTAINING COMPOUND.

United States Patent Oflice 3,701,804 Patented Oct. 31, 1972 3,701,804 PROCESS FOR ADIPIC ACID MANUFACTURE Walter H. Knoth, Jr., Mendenhall, Pa., and George W. Parshall, Wilmington, Del., assignors to E. I. du Pout de Nemours and Company, Wilmington, Del. No Drawing. Filed Mar. 19, 1971, Ser. No. 126,345 Int. Cl. C07c 55/14 US. Cl. 260530 R 5 Claims ABSTRACT OF THE DISCLOSURE Disclosed herein is a process for the manufacture of adipic acid, a reactant in the preparation of 6,6 nylon, comprising reacting cyclohexene and acetaldehyde in the presence of oxygen and a catalyst consisting of a salt of one of the metals vanadium, tungsten, molybdenum, osmium or ruthenium, said process optionally employing a cocatalyst consisting of an inorganic nitrogen-containing compound.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention concerns a new process for the preparation of adipic acid in which acetic acid is a desirable secondary product.

(2) Description of the prior art The nitric acid oxidation of cyclohexene to adipic acid with vanadium catalysis is known. See: US. Pat. 2,323,- 861, British Pat. 1,068,905, French Pat. 981,609, and J. Franz and W. Knowles, Chem. and 1nd,, 1961, 250. These prior art processes, quite distinct from the novel process taught herein, suffer from the disadvantage of having reaction systems containing extremely corrosive nitric acid.

SUMMARY .AND DETAILS OF THE INVENTION Cyclohexene and acetaldehyde are reacted in the presence of oxygen and a primary catalytic compound of one of the metals vanadium, tungsten, molybdenum, osmium or ruthenium to form adipic acid and acetic acid.

Although it is desired not to be bound to any theory concerning the mechanism of reaction, it is believed that the following equations represent the major reaction paths:

1. CHzCHO 0 CH COOOH acetaldehyde peracetic acid 7 2. v a Q CHaCOOOH CHaCOOH /O 2 o 011, 0 0 0H catalyst adipic acid The proportions of cyclohexene and acetaldehyde which may be brought together in the process of this invention may be varied widely since at least some adipic acid and acetic acid will be formed even at :1 or 1:100 molar ratios, respectively. For practical yields, it is preferred to employ ratios between 3:1 and 1:15, and best yields are obtained when the respective molar ratios are between 1:1 and 1:5.

For the reaction to proceed economically, there should be present at least an equivalent amount and preferably a slight molecular excess of oxygen. Excess oxygen up to 100 fold may be employed but there is no advantage in extremely high oxygen proportions. Oxygen may be supplied to the reaction in the form of pure oxygen gas or in a gas mixture containing substantial quantities of oxygen along with inert materials as in air.

The metal catalyst is reduced in Equations 4 and 5 above but under the reaction conditions it is rapidly reoxidized. The catalyst may be any compound of the selected metals in which the metal is capable of facile valence change. The metal compound supplied to the reaction may contain the metal in any of its positive valence states. The amount of catalyst, expressed as metal, can range from 0.001 to 10% of the weight of the reaction mixture of cyclohexene and acetaldehyde. It is preferably in the range of 0.01 to 5% of this weight.

Some of the primary catalytic compounds contemplated to be employed alone or in combination are listed below.

Vanadium: ammonium meta-vanadate, vanadium ace.- tylacetonanes, vanadyl acetylacetonate, vanadium, pentoxide, vanadic acid, the metal vanadates, vanadium oxy chloride, vanadyl naphthenate, vanadyl dichloride, vanadyl sulfate;

Tungsten: tungstic acid and its salts such as sodium and lithium tungstate, sodium phosphotungstate, sodium tungstosilicate, tungsten dioxide, tungsten trioxide, tungsten pentoxide, tungsten oxydichloride, tungsten oxytetrachloride;

Molybdenum: ammonium molybdate, sodium molybdate, molybdenum dioxide, molybdenum trioxide, molybdenum pentoxide, molybdenum sesquioxide, sodium phosphomolybdate, molybdenum oxydichloride, molybdenum oxytrichloride, molybdenum oxytetrachloride;

Osmium: osmium monoxide, osmium dioxide, osmium tetroxide, osmium sesquioxide, potassium osmiate;

Ruthenium: ruthenium dioxide, ruthenium tetroxide, and ruthenium nitrate.

Some of these catalytic compounds contain the metal in its catalytically active state. In others the metal is oxidized under the reaction conditions to a catalytically active form.

An inorganic nitrogen-containing cocatalyst can be employed to aid in the reoxidation of spent metal catalyst. Said cocatalyst can be one or more inorganic metal nitrate(s) and/or nitrogen oxide(s). The inorganic nitrate(s) may be any metal nitrate(s), however, alkali metal nitrates and alkaline earth metal nitrates are preferred. Particularly preferred are lithium, sodium and potassium alkali metal nitrates and magnesium and calcium alkaline earth metal nitrates. Operable nitrogen oxides include N 0, NO, N 0 N0 N 0 and N0 The amount of cocatalyst(s) used may be up to 300% by weight of the metal in the primary catalyst.

The process of this invention may be carried out over a wide temperature range, particularly from 20 to 200 C. Preferred temperatures are in the range from 15 to C., temperatures of up to about 60 C. being preferred with, vanadium catalysts and temperatures over 60 C. being preferred with tungsten, molybdenum, osmium and ruthenium catalysts.

Pressure is not a critical variable in the process of this invention and pressures both above and below atmospheric may be employed. Preferred pressures are in the range from 1 to 60 atmospheres, and particularly preferred are pressures in the range from 1 to 15 atmospheres. When air is used as the oxidant, it is customary to employ pressures up to about 2 times those correspondfallento about 30 p.s.i.g.; however, this did not seem to affect the results.

After the reaction period, excess pressure was vented slowly at ambient temperature, and a weighed amount of ingly employed with pure oxygen. 5 toluene or xylene was added to serve as a standard for The reaction of this invention is usually essentially comquantitative gas chromatographic analysis. The crude plete within a period of 1-20 hours. Longer periods are mixture was then analyzed for the 'volatile constituents, permissible and shorter periods (to a minimum of 15 including recovered acetaldehyde, cyclohexene, acetic acid minutes) may be used with some sacrifice in yield. and 2-acetoxycyclohexanol, by gas chromatography on a The addition of a liquid reaction medium in the proc- Varian Aerograph Series 1700 instrument. The gas chroess of this invention is not essential since the reaction can matographic columns were stainless steel (6 x A") and be carried out neat. If desired, a liquid which is relatively were packed with 20% Triton X305 (octylphenoxyoxidation-resistant, such as acetic acid, ethyl acetate, benpolyethylene glycol) on 60-80 mesh Chromosorb W" zene, tertiary butanol or water may be employed as a Regular (diatomaceous earth which has been flux-calcined diluent. with sodium carbonate and then waterwashed). The col- I umns were programmed from 80-200 C. at 6 C./min- PREFERRED EMBODIMENTS 0F ute with an injector temperature of 180 C.

THE INVENTION For detection of the carboxylic acids formed in the The following nonlimiting examples are meant to i11us experiment, the readily volatile materials were removed trate the invention. Percentages are by weight and stirring undel: reduced Pressre from the remamder crufie is maintained throughout the reaction period. All yield reactlonProdPct- A known amount of Peptanolc, Pimehc, figures are based on cyclohexene charge Examples 2, or azelaic acid was added to the residue to serve as a 20 27 and 31 have been included for comparative standard for gas chromatographic analysis. The reaction purposes mixture was then treated by one of two procedures (A EXAMPLE 1 25 or B, below), both designed to convert all of the carboxylic acids present to their methyl esters, which are Acetic acid (1 ml.), acetaldehyde (2 ml.), cyclohex sufficiently volatile to detect and measure by gas chroma- (1 ml.) and ammonium metavanadate, NH VO (0.1 g.) togfaPhic analysiswere charged to a 375-ml. glass pressure bottle. This wa The following analytical procedures were employed in hill d to b ut 78 C, d fl h d i h oxygen I was the manner described to determine the content of the h pressured to 50 i, i h oxygen d h d t reaction products made herein. ProcedureAwas employed 60 c. at. autogenous pressure. A leak developed after to determine the products in Examples 1 and 3 and 15 minutes and little pressure could be maintained for eedure B was p y to determine the products in the remainder of the reaction period (1.75 hours). Dep es 2 a 0 9- spite this, analysis of the product revealed a desirably 35 Procedure milliliters f a o ti 0f high 4:1 ratio of adipic acid to glutaric acid (by-product). boron trifluoride n methanol was added'to the p tion residue containing the reference acid. The mixture [EXAMPLES 2 TO 19 was heated on a steam bath for two minutes and then 40 diluted with 30 ml. of water followed by three extrac- TheSe examples are Presented Table Example 2 tions with 30 ml. portions of hexane. The extracts were therein shows the inferior results obtained in the absence bi d, concentrated t about 4 m1, and analyzed by of the metal catalyst taught herein. gas chromatography using the equipment described above.

Examples 2 i0 19 were all conducted as follows! The Procedure B, This is preferred to Procedure A ber a t including catalysts and y solvent used, were cause it is more rapid and slightly more accurate. The charged to a glass Pressure bottle- This was chilled evaporation residue containing the standard acid was ditO about and flushed with Y The System luted with 10 ml. of methanol. It was then basified with was made Pressure tight, the cooling bath was removed tetramethylammonium hydroxide and subjected to gas and Oxygen was admitted to 44-46 P- while the bottle chromatographic analysis using the equipment described was still cool. The temperature was then brought to the above, except that the injector temperature was about desired level. In some instances the pressure vessel was re- 300 C. The tetramethylammonium carboxylates pyrolyze pressured with oxygen to 45 p.s.i.g. when the pressure had to the methyl esters at this temperature.

TABLE 1 Percent Acetalyield 0! Cyclodehyde NH4V0; LiNOs Temp. Reaction adipic Example hexane (ml.) Solvent (ml.) (g.) (g.) 0.) time (hrs.) acid 4 21-24 20.0 0.3 3 1011300011 g: 3 25.0 a ICHsCOOH 85 3.5 12.5 3 ICH COOH 80 5.5 13.3 4 4.0 17.5 3 1 01 1360011 21-24 5.5 18.2 4 2011,0003 21-24 94 21.6

4 $328 21-24 17 4s 5 icfisoggg 21-24 21 14.0 4 fif 21-24 18 v 12.9 4 1 011,00 21-24 17 20.4 3 1cHic00H 40 0 5.6 a 1 oHicoocim 21-24 11 20.2 4 101100011 21-24 10 22.5 4 1 021,000 21-24 16 17.9 3 85%? 21-24 16 14.3 4 1 CHaCOOH 21-24 18 10.1 1 1 CH COOCgHg 21-24 21 19.9

a This example was conducted at 200 p.s.i.g. of oxygen in a glass lined stainless steel pressure vessel. b The catalyst was vanadium (III) acetylacetonate.

v The catalyst was vanadium oxyacetylaeetonate.

d The catalyst was vauadyl naphthenate.

5 EXAMPLES 20 TO 39 These examples are summarized in Table 2. The procedural details are generally the same as for Examples 1 to 19 except that Examples 20 to 39 were conducted in a 125 ml. glass pressure bottle, rather than a 375 ml. bottle. Reactants included 2 ml. of acetaldehyde and 0.5 ml. of acetic acid in addition to the reactants listed in the table.

High yields and the process of this invention The particular disclosed catalysts are extremely important to produce high yields of adipic acid. The importance of these catalysts to the novel process is underscored in view of the absence of nitric acid that is employed in some prior art processes as the oxidant for cyclohexene.

When no catalysts are employed, yields are very low as can be seen from comparative Examples 2 (Table 1) and 20, 25, 27 and 31 (Table 2). In fact, yields are almost nil in Examples 2 and 20. To attempt substitution of other catalysts (undisclosed herein) in the process as taught would result in no adipic acid being formed, or, in the production of lower yields than are possible to achieve with the process of this invention.

The superiority of the novel process is borne out by the surprisingly high yields of adipic acid obtained herein. For instance, Example 36 shows a yield of 33%. Superiority of the novel process is also shown by the generally high yields obtained at relatively low temperatures.

TABLE 2 Percent Cyclo- Catalyst yield, hexene (0.1.g. of Temp, Time, adiplc Example number (g.) each) hrs. acid 0. 30 None 21-24 18 1 0. 31 NH4VO 21-24 2% 12. 7 0. 32 NH4VOz..-. 21-24 18 22. 8 0. 30 21-24 66 5. 2 0. 30 21-24 18 7. 0. 31 40 17 7. 2 0. 30 40 18 16. 8 0. 31 60 18 7. 2 0. 30 60 20 13. 8 0. 30 60 17 10. 0 0. 30 60 17% 22. 0 0. 31 80 2% 1. 1 0. 31 80 2% 12. 7 0. 30 80 3 22. 0 0. 30 M0030--- 80 3 29. 4 0. 30 Ruoz 80 2 23. 8 0. 30 0s0. v,o. 80 3% 33. 0 0. 34 mm 80 31 16. 6 0. 31 HWO 100 2 18. 1 0. 31 M00: 100 2 27. 7

We claim:

1. A process for making adipic acid comprising reacting cyclohexene and acetaldehyde at molar ratios of 100:1 to 1:100, in the presence of at least one equivalent of oxygen and a catalytic compound of one of the metals vanadium, tungsten, molybdenum, osmium, ruthenium, or combinations thereof, in an amount, expressed as metal, of from 0.001% to of the combined weight of cyclohexene and acetaldehyde, at a temperature between about -20 to 200 (3., wherein the catalytic compound is selected from the group consisting of ammonium metal-vanadate, vanadium acetylacetonates,

vanadyl acetylacetonate, vanadium pentoxide, vanadic acid, the metal vanadates, vanadium oxychloride, vanadyl naphthenate, vanadyl dichloride, vanadyl sulfate; tungstic acid and its sodium and lithium tungstate salts, sodium phosphotungstate, sodium tungstosilicate, tungsten dioxide, tungsten trioxide, tungsten pentoxide, tungsten oxydichloride, tungsten oxytetrachloride; ammonium molybdate, sodium molybdate, molybdenum dioxide, molybdenum trioxide, molybdenum pentoxide, molybdenum sesquioxide, sodium phosphomolybdate, molybdenum oxydichloride, molybdenum oxytrichloride, molybdenum oxytetrachloride;

osmium monoxide, osmium dioxide, osmium tetroxide,

osmium sesquioxide, potassium osmiate;

ruthenium dioxidee, ruthenium tetroxide, and ruthenium nitrate.

2. A process according to claim 1, wherein the molar ratio of cyclohexene to acetaldehyde is between 3:1 to 1:15, respectively, and wherein there is a molecular eX- cess of oxygen, an amount of catalytic compound of from 0.01% to 5% of the combined weight of cyclohexene and acetaldehyde, and the temperature is between about 15 to C.

3. A process according to claim 2, wherein the molar ratio of cyclohexene to acetaldehyde is between 1:1 to 1:5.

4. A process according to claim 2, employing a cocatalyst selected from the group consisting of alkali metal nitrates, alkaline earth metal nitrates and nitrogen oxides, said cocatalyst present in an amount up to 300% of the weight of the metal of the catalytic compound.

5. A process according to claim 4, wherein the cocatalyst is at least one member selected from the group consisting of lithium, sodium, potassium, magnesium and calcium nitrates, and N 0, NO, N 0 N0 N 0 and N0 References Cited UNITED STATES PATENTS 3,346,473 10/1967 Colfey et al. 260530 R X FOREIGN PATENTS 1,076,455 7/1967 United Kingdom 260-533 C OTHER REFERENCES Triebs et al.: Chem. Ber., 86, pp. 616-25 (1953)abstract only.

LORRAINE A. WE'INBERGER, Primary Examiner R. D. KELLY, Assistant Examiner U.S. Cl. X.R. 260-5 33 C UNITED STATES PATENT OFFICE (s/sa) CERTIFICATE OF CORRECTION Patent No. 3 ,70l,80l+ Dated October 31, 1972 n Walter H. Knoth. Jr. and Geor e W. Parshall 7 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 1, line 55, "cyclohexene acid" should be cyclonexene oxide Col. 2, v line 29, "ony chloroshould be oxychlor'o- 7 Col. 3, Example 10, acetaldehyde amount should be "1+" Col. 5, Example 28, cetalyst should be NH vo Col. 6, line 3, correct the spelling of metavanadate and line 20, correctthe spelling of dioXide--.

Signed and. sealed this 8th day of May 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents UNITED STATES PATENT oFFLcE CERTNCATE 0F QUREfiTiGN Patent No Dated OCtOber 31 Inv r WALTER H9 KNO'I'H, JR., ET. AL.

It is certified that error appears in the above-identified patent and that said Letters Petent are hereby corrected as shown below:

Column 2, line 28, after "vanadium", cancel the comma and 'tylacetonanes" should read tylacetonates Signed and sealed this 20th day of November 1973.

(SEAL) Attest: I

EDWARD M.FLETCHER,JR. RENE D. TEG'IMEYER Attesting Officer Acting Commissioner of Patents FORM PO-1OSO (10-69) USCOMM-DC 60376-P69 i: uvs, GOVERNMENT PRINTING OFFICE I969 0-366-334, 

